Such a method, central station, terminal station network system and frames are already known in the art e.g. from the IEEE 802.14 contribution (Dallas May 1995) "ATM-based Hybrid Fiber Coax System" by Peter Vandenabeele and Chris Sierens. Therein a system is described over which broadcast video and interactive services are provided by a central station for a plurality of terminal stations. The video services are provided by means of downstream RF channels containing an MPEG2 Transport Stream (MPEG2-TS), while the interactive services are provided using downstream RF channels containing a frame with a combination of Asynchronous Transfer Mode (ATM) cells and TDMA control information, i.e. Access Grant Information (AGI) to control the sending of upstream frames from the terminal station to the central station. Two types of modes are defined in this document : a standard mode and a high mode. In standard mode the frame contains 748 bytes split in 6 bytes for TDMA control information and the rest for ATM cells, and in high mode the frame contains 6 bytes for TDMA control information and 181 bytes for ATM cells. The latter frame is used for high upstream bit rates.
Since the number of bytes foreseen in these frames for TDMA signalling and thus also the number of AGI is restricted, it is clear that there is also a restriction in this system on the upstream data rate and on the relation between the upstream and downstream rates, the upstream data rate being the sum of the data rates of all upstream channels controlled by one downstream channel. Additionnally only a fixed number of terminal stations can be controlled by one downstream frame.